((a)) ** .—** The Secretary of the Army or Secretary of the Air Force, within the limits of appropriations that may be available for that purpose, may assemble in camp at such season of the year and for such period as the Secretary of the Army or Secretary of the Air Force may designate, at the field of military maneuvers, such portions of the military forces of the United States as the Secretary of the Army or Secretary of the Air Force may think best, to receive military instruction there. The Secretary of the Army of Secretary of the Air Force may detail instructors from the Regular Army or Regular Air Force, respectively, for those forces during their exercises.
((b)) ** .—** The Secretary of the Army or Secretary of the Air Force may prescribe regulations governing the assembling of the National Guard or militia of the States on the maneuvering grounds.